Climate Prediction Center

US HAZARDS ASSESSMENT
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT JULY 03 2009

SYNOPSIS: VERY WARM, HUMID AIR FROM THE GULF OF MEXICO IS FORECAST TO PREVAIL ACROSS THE DEEP SOUTH EARLY IN THIS ASSESSMENT PERIOD, WHILE LOW PRESSURE AND COOL, DAMP WEATHER PERSISTS IN THE NORTHEAST. A NEARLY STATIONARY FRONTAL ZONE IS PREDICTED TO SPAN THE SOUTH FROM ARKANSAS EASTWARD TO THE CAROLINAS. THIS ZONE WILL LIKELY SERVE AS A FOCUSING MECHANISM FOR SHOWERS AND STORMS. CONCURRENTLY, STRENGTHENING HIGH PRESSURE OVER THE GREAT PLAINS IS FORECAST TO BRING ABOVE NORMAL TEMPERATURES TO THE REGION. ACROSS THE WEST, SCATTERED SHOWERS AND THUNDERSTORMS ARE ANTICIPATED THROUGHOUT THIS PERIOD.

HAZARDS

MUCH ABOVE-NORMAL TEMPERATURES FOR THE SOUTHERN HIGH PLAINS, JULY 9TH.
HEAVY RAINS IN LOWER MISSISSIPPI VALLEY, JULY 6-7.
ONGOING FLOODING FOR EASTERN PARTS OF THE DAKOTAS.
PERSISTING DROUGHT ACROSS PARTS OF CALIFORNIA, NEVADA, NEW MEXICO, TEXAS AND WISCONSIN.

DETAILED SUMMARY

FOR MONDAY JULY 06 - WEDNESDAY JULY 08: A LOW PRESSURE SYSTEM IS FORECAST TO PERSIST OVER THE NORTHEAST, BRINGING PERHAPS ANOTHER INCH OF RAIN TO PORTIONS OF NORTHERN AND CENTRAL NEW ENGLAND. WITH RIVERS AND STREAMS ALREADY NEAR FLOOD STAGE, THE ADDED PRECIPITATION MAY BE ENOUGH TO CAUSE MINOR FLOODING IN THE REGION. OTHER AREAS OF THE COUNTRY WHICH HAVE RIVERS AND STREAMS NEAR OR ABOVE FLOOD STAGE INCLUDE WESTERN WYOMING, EASTERN IDAHO AND SOUTHERN MONTANA, AS WELL AS THE JAMES RIVER IN EASTERN SOUTH DAKOTA. THE JAMES RIVER IS LIKELY TO CONTINUE OVERFLOWING ITS BANKS FOR THIS PERIOD.

ELSEWHERE, A NEARLY-STATIONARY FRONT IS PREDICTED TO EXTEND ACROSS THE SOUTH, FROM OKLAHOMA TO THE CAROLINAS. THIS FRONT WILL LIKELY SERVE AS A FOCUSING MECHANISM FOR SHOWERS AND THUNDERSTORMS DURING THE PERIOD. UP TO 2.5 INCHES OF RAIN COULD FALL IN A BAND FROM NORTHEAST TEXAS TO THE FLORIDA PANHANDLE, AND EVEN HEAVIER AMOUNTS ARE EXPECTED JUST OFF THE CAROLINA COAST.

IN THE PACIFIC NORTHWEST, LOWERING 500-HPA HEIGHTS WILL BE ACCOMPANIED BY THE APPROACH AND PASSAGE OF A COLD FRONT. AS THIS SYSTEM MOVES EASTWARD ACROSS THE PACIFIC NORTHWEST, IT MAY BE PRECEDED AND ACCOMPANIED BY HIGH-BASED, LOW PRECIPITATION THUNDERSTORMS. IN THE SOUTHWEST, AN EXPECTED DECREASE IN MONSOON ACTIVITY SHOULD RESULT IN A FAIRLY DRY PERIOD FOR ALL BUT FAR SOUTHEASTERN PARTS OF ARIZONA, AND NEW MEXICO.

A RELATIVELY TRANQUIL WEATHER PATTERN IS ANTICIPATED IN ALASKA, AS A BERING SEA LOW PRESSURE CENTER TRACKS NORTHWARD, WHILE A COLD FRONT DISSIPATES OVER THE INTERIOR.

FOR THURSDAY JULY 09 - MONDAY JULY 13: THE UPPER LEVEL TROUGH IN THE NORTHWEST IS EXPECTED TO BRING UNSEASONABLY COOL AIR TO THE WEST. WEAK RIDGING IS FORECAST TO MOVE ACROSS THE PLAINS AND MISSISSIPPI VALLEY, WHILE A LOW PRESSURE SYSTEM MOVES WELL OUT OVER THE WESTERN ATLANTIC. AT THE START OF THIS PERIOD, ABOVE AND MUCH ABOVE NORMAL TEMPERATURES ARE FORECAST OVER THE GREAT PLAINS, ASSOCIATED WITH AN UPPER-LEVEL RIDGE. PORTIONS OF THE SOUTHERN AND CENTRAL HIGH PLAINS ARE EXPECTED TO BE ABOUT 8 DEGREES ABOVE NORMAL. THIS REGION TYPICALLY EXPERIENCES HIGHS AROUND 90 DEGREES F AT THIS TIME OF YEAR, SO EXPECT HIGHS IN THE UPPER 90S TO NEAR 100 DEGREES F.

IN THE ALASKA REGION, WEAK LOWS ARE EXPECTED TO PROGRESS ACROSS THE BERING SEA AND AFFECT THE SOUTHWESTERN PORTIONS OF ALASKA, WHILE DRIER CONDITIONS ARE FORECAST ACROSS THE SOUTHEASTERN PANHANDLE.

FOR TUESDAY JULY 14 - FRIDAY JULY 17: ALL OF THE DYNAMICAL MODELS ANTICIPATE WEAK HEIGHT ANOMALY PATTERNS ACROSS THE CONUS. THE ENSEMBLES GENERALLY FAVOR WEAK TROUGHS NEAR THE EAST AND WEST COASTS, AND A WEAK RIDGE OVER THE NATION'S MIDSECTION. THE 0Z AND 6Z OPERATIONAL GFS SOLUTIONS SUGGEST SOMEWHAT MORE RIDGING CENTERED OVER THE MIDDLE MISSISSIPPI VALLEY. NO SPECIFIC HAZARDS CAN BE RELIABLY DEPICTED ON THE COMPOSITE MAP AT THIS TIME RANGE, WITH THE EXCEPTION OF PERSISTENT DROUGHT AREAS OVER PORTIONS OF CALIFORNIA, NEVADA, NEW MEXICO, TEXAS AND WISCONSIN.

FORECASTER: ANTHONY ARTUSA

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